Why Coffee Makes Me Tired and Sleepy Instead of Active?

Is coffee making you tired?

Instead of making you feel active and alert, why do you think your energy being sapped out of your body after drinking your daily dose of coffee? If you haven’t wondered why coffee makes you sleepy then it’s high time you should know why.

You might not know that the caffeine found in coffee stimulates the central nervous system, the heart, and muscle. And drinking too much coffee increases your tolerance to caffeine, which leads to caffeine crash and brings your alertness level to an all-time low. So, you might conclude that caffeine can make you tired, and you'd be right! But that isn’t the only fact you should know when it comes to the effects of regular and excessive coffee drinking.

At this point, you might still be wondering, “but why does coffee make me tired, exactly?” If you're suffering from caffeine crash symptoms and want a more in-depth look at why, exactly, this is happening, read on.

Demystifying caffeine in coffee

We know your coffee is already part of your day and we don’t want to discourage you from drinking it, but it's taking its toll on your body.

Is it caffeine that’s making you feel sleepy a few hours after drinking coffee?

The answer is: there is a chemical in your brain called adenosine which makes you drowsy and leads to sleepiness at night. This chemical has been prevented from doing its job every time you drink a cup of coffee. This happens when you decide to study or work overtime and when you decide you need a boost to make it through the day.

What adenosine does to your body

But what really happens with or without adenosine in your body? A video from ASAP science video explains “While you sleep, the concentration of adenosine declines, gradually promoting wakefulness.” The more adenosine that builds up, the sleepier you feel.

Essentially, caffeine hijacks adenosine receptors because your brain cells look at it like adenosine. It has a similar shape and once it gets its rightful spot, it leaves a lower number of receptors for adenosine to stick to, which in turn reduces your sleepiness. However, all that adenosine that can't do its job thanks to caffeine doesn't go away, and it keeps being produced all the while, meaning your brain is flooded with more adenosine than usual when the caffeine wears off, leading to a caffeine crash and sleepiness.

Without adenosine, “our natural stimulants run wild,” Joseph Stromberg writes in Smithsonian. You’re going to feel wide awake and alert—for a while. But all good things must come to an end, and your brain quickly wises up to your tricks.


For coffee lovers and coffee addicts, caffeine is our go-to drug of choice. When our energy’s down during midday or after waking up in the morning, we reach out for a cup of coffee to brighten up our mood. But have you ever skipped your usual espresso shot or other beverage of choice only to feel more tired? Ask yourself again, why does coffee make me tired?

Can caffeine in coffee make you tired? Yes, but genetics may also play a role.

“There are clear genetic variations on how certain individuals metabolize caffeine (fast metabolizers vs. slow metabolizers),” says Kristin Kirkpatrick, RD, Cleveland Clinic Manager of Wellness Nutrition Services. “The test looks at how quickly or slowly someone breaks down caffeine based on variants of a certain gene (called the CYP1A2 gene) to determine if caffeine is beneficial or harmful to your health,” says Kirkpatrick.

There may even a gene that makes you so fond of drinking coffee .

Fatigue and disturbed sleeping cycle

If your habit is interfering with your regular sleep cycle or causing you to experience bouts of energy followed by deep fatigue, it may be time to cut either cut back a little or wean yourself off altogether. Because caffeine helps you to become alert, it can confuse your nervous system into prompting your body not to sleep and it can affect your ability to enter a deep sleep cycle. This way, excess caffeine intakes can set off a harmful cycle in your body.

For example, you may drink caffeine to feel more alert. However, the caffeine keeps you from going to sleep, which makes you drowsy. The circle continues when you drink more caffeine during the day to reduce feelings of drowsiness. Over time, this fatigue can culminate in chronic insomnia, or an inability to fall into a deep sleep.

“Caffeine is a stimulant, so theoretically, consuming it should increase blood pressure, heart rate and increase alertness and energy; but the effects may be temporary, and once the caffeine is worn off, your fatigue may feel worse,” expresses Kirkpatrick.

Does caffeine dehydrate you?

The idea that caffeine can cause dehydration can be traced to a study performed in 1928 where increased urination in people who drank caffeinated beverages, and suggested that caffeine was a diuretic, according to Lawrence Armstrong, a professor in the Department of Kinesiology at the University of Connecticut and director of the Human Performance Laboratory.

Now, there’s a study showing that evaluated hydration indicators, including urine volume, were similar for all of the treatment groups.

This finding demonstrates that, fortunately, caffeine does not have a dehydrating effect when compared to the control group. The scientists also found that a higher dose of caffeine isn’t any more likely to dehydrate a person than smaller doses were.

You are probably wrong

If you're a long-time coffee drinker, you may think that you've felt this “diuretic” effect at times, as drinking coffee can definitely make you pee more than most other drinks. This was observed in a recent study looking at urine volumes produced in the two hours after drinking a range of drinks, where the fluid loss from coffee was greatest.

But the good news is, the key thing that’s often not talked about is that when you take note about the fluid that is rapt and retained from the coffee itself, the diuresis that coffee drinking ostensibly causes does not appear to show a net fluid loss over a longer span of time.

Concerns about excessive caffeine consumption as well as harmful interactions with other drugs such as alcohol, require further research. But based on the available data, your daily cup of coffee is not terribly likely to dehydrate you, and it might just have some added health benefits while getting you through your day: just remember, all things in moderation!

It’s more than just the side-effects

Caffeine, the most widely consumed psychoactive substance in the world, has many beneficial effects, which you can read about here. Its benefits have been researched a great deal, but coffee is a complex drink comprised of many different substances.

Coffee can help you live a longer and healthier life. Coffee contains lots of antioxidants that help the body fight chemicals called “free radicals,” which may pose dangerous effects to your health. Also, drinking coffee can help you burn fat.

If you want to decrease your total caffeine consumption, try switching out a portion of your coffee for decaffeinated, or consider brewing your tea for a shorter time. Also consider the fact that no amount of coffee or caffeine is going to make up for tons of lost sleep or the energy-sapping effects of living an unhealthy lifestyle.

Gregory Tumlin

Gregory Tumlin editor of agreatcoffee.com has worked in the coffee industry for 5 years now. He used to work at Coffee and Espresso Bar in Princeton, NJ and have done some side coffee consulting and training through Barista School. He is also a husband and father of a young boy as well as a masters student. In whatever spare time he has left, Gregory enjoys running, cycling and reads just the right amount of trashy romance novels.

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Chris - November 29, 2018

But what if you’re not addicted to it and only have a cup every now and again, like once a week. Every time I drink a cup of coffee black or sweetened it makes me want to take a nap. If I have up to 3 cups in a sitting I will not be able to hold my eyes open at all. I can have a cup in the evening right before bed, especially if I’m really stressed out and it helps me relax and get a good nights rest. I guess this is more for those who are dealing with the side effects of the addiction.


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